The PVWatts® energy estimate is based on an hourly performance simulation using a typical-year weather file that represents a multi-year historical period for for a Fixed (open rack) photovoltaic system. The kWh range is based on analysis of a nearby data site described here.
The estimate for the value of this energy is the product of the AC energy and the average retail electricity rate. This value is useful for basic comparisons but does not account for financial considerations in a cash flow-based analysis. All of these results are based on assumptions described in Help that may not accurately represent technical or economic characteristics of the project you are modeling.